On the AO3, you can easily subscribe to an author, to receive notifications whenever that person posts a new story. You can also subscribe to a series or a work, to receive notifications for new installments.

Can you subscribe to a fandom, to receive notifications whenever a new work is posted in that fandom? Of course that wouldn't be practical for the large, busy fandoms, but it could be outstanding for small, sleepy fandoms, especially ones that see only a few stories a year.